Cytokines, as biological response modifiers, may (i) stimulate non-specific immune mechanisms, and (ii) elaborate and/or augment specific immunity generated by vaccines. The novel method of genetic immunization, which involves eliciting immune responses by inoculation of a plasmid vector expressing an antigen(s) of an infectious agent, has shown efficacy in several animal models. Additionally, recent studies have demonstrated that co-injection of rodents with plasmids expressing a test antigen and a cytokine can enhance the immune response to the antigen. To test the potential of such adjuvant effects of cytokines for AIDS vaccines, the applicants will use the non-human primate model of simian-human immunodeficiency virus (SHIV) infection of rhesus macaques. Cytokines selected for this study are based on knowledge of immunomodulatory effects that might augment anti-viral immune responses, as well as the results of empirical studies on adjuvant effects in animals and humans. These cytokines are granulocyte-macrophage colony stimulating factor (GM-CSF) and interieukin-12 (IL-12). The hypothesis is that co-injection of macaques with plasmids expressing a cytokine and SHIV antigens can elicit immune responses that protect from viral infection and development of a fatal AIDS-like disease. Three specific aims have been proposed to address this hypothesis: (i) optimization of plasmid vectors for expression of cytokines and SHIV antigens in vitro in mammalian cell cultures; (ii) analysis of anti-viral immune responses in vivo in macaques co-injected with plasmids expressing cytokines and viral antigens; and (iii) challenge of these immunized macaques with pathogenic SHIV. Knowledge gained from investigations of cytokine vectors as potential adjuvants in non-human primates may facilitate the design of efficacious vaccines for HIV infection and AIDS as well as for other infectious agent.